my opponent forfeited and with a wink of an eye my laptop turned off.
This may be two independent actions.
Players have quit the game all the time, but usually the other(s) may continue in stroke play after some waiting for the clock to run out.
Such immediate crash of your computer might be a new(?) error in the game as a response to the quitting.
You may inform WGT ("Contact" below), but it might be worth it only after the next crash.